\documentclass[11pt,openright]{book}
\usepackage{array}
\newcolumntype{C}{>{\centering\arraybackslash}X}
\renewcommand{\arraystretch}{1.2}
\usepackage{booktabs}
\usepackage{tabularx}
\usepackage{caption}
\usepackage{threeparttable}

\begin{document}



\def\onepc{$^{\ast\ast}$} \def\fivepc{$^{\ast}$}
\def\zeropc{$^{\ast\ast\ast}$}
\begin{table}
\centering
\scriptsize
\caption*{Likert+ Treatment vs. Likert/QVSR (pooled) \label{bal2}}

\input{bal2.tex}


\begin{tablenotes}
        \item \fivepc $p$\textless.05, \onepc $p$\textless.01 \zeropc $p$\textless.001.
        \item See notes Table \ref{bal1}.
\end{tablenotes}
\end{table}


\end{document}